Interferon (IFN) is initially discovered in 1957 by Alick Isaacs and Jean Lindenmann during research of influenza virus. After infected by virus, the host cells immediately secrete a cytokine to induce other cells nearby to produce antiviral proteins to interfere with viral replication. This cytokine is later named IFN. Since the first discovery of IFN, three types of IFN have been identified—type I IFN (IFN-α and IFN-β), type II IFN (IFN-γ), and type III IFN (IFN-λ). The antiviral effects of IFN are mainly provided by type I IFN (IFN-α and IFN-β). In addition to antiviral activities, IFN has anti-tumor activity, and can induce cell differentiation and modulate immune response.
So far, the majority of commercial IFN is used for the treatment of human diseases, such as human hepatitis B, human hepatitis C, Kaposi's sarcoma (KS), and malignant melanoma.
Without an effective vaccine for preventing an animal virus, an infected animal of the virus can only be treated with supportive therapy. However, supportive therapy is usually ineffective, and therefore the infection of animal virus may cause great economic losses in livestock husbandry.
Therefore, it is important to develop IFN having antiviral activities against animal viruses.